The Little Duck that Might

With a bit of help, Hawai`i's endangered koloa has a shot at recovery

Story by Rachel Davies.

2015 is shaping up to be a big year for an independent little brown duck called the koloa maoli.

Otherwise known as the Hawaiian duck or Anas wyvilliana or simply the koloa, it’s an endangered species with an estimated population of two thousand—and even with all of those names, most people have never heard of it. “When I tell people I’m working with the Hawaiian duck,” says Oregon State University PhD student Christopher Malachowski, “they say, ‘Oh! The nēnē!’”—confusing the duck with the Hawaiian goose. Almost everyone who works with the koloa can tell a similar tale, but they don’t mind. “I have a soft spot in my heart for little brown birds that nobody pays attention to,” says Kim Uyehara, biologist at the Hanalei National Wildlife Refuge on Kaua‘i. “People see it out on the marsh, and they can’t really connect to it,” says Andy Engilis, longtime champion of the koloa. “But if you’ve ever held a Hawaiian duck, they’re a very charismatic little bird.”

While the vast majority of endemic duck species in Hawai‘i went extinct with the coming of humans, the koloa have managed to hang on—but just barely.

Courtesy Christopher Malachowski

If you’re ever lucky enough to hold a koloa, you’ll have your arms around a tidy dabbling duck about two-thirds the size of a mallard, with a small beak, sparkling eyes and rich, deep brown plumage (though its coloring does vary subtly with its stages of life and by gender). The koloa once lived on all the Hawaiian islands and could be found anywhere from sea level to ten-thousand-foot elevation; the duck is an expert at navigating the steep valleys and lush forests found deep in the seclusion of Hawai‘i’s mountains. In fact, the koloa is so private that it’s only in the last decade that we’ve been able to learn much about it.

The qualities that have kept the koloa out of the public eye—its shyness, its swift departure whenever a perceived threat comes near, its precocious attitude—have been key to its survival in an environment in which most other endemic waterfowl are now extinct. Just a couple of thousand years ago in Hawai‘i, the koloa rubbed feathers with a marvelous collection of fellow duck species, all of them having evolved in the seclusion of the Islands, which were then free of any mammalian predators. Fossils unearthed in the Makauwahi Cave on the south coast of Kaua‘i comprise about a dozen unique duck species in total, including a ﬂightless duck as large as a goose that grazed on grasses much like a cow or sheep; a nocturnal, mole-like duck; and a duck with a wide, deep bill akin to the jaw of a tortoise. Yet the only duck to have survived the coming of man to the main Hawaiian Islands is the secretive koloa. Farther north the Laysan duck (A. laysanensis) survives on the atolls of Midway, Laysan and Kure. Both species have barely squeaked through, with their populations dwindling perilously low at points over the last century.

Today the ducks' stronghold is the Hanalei National Wildlife Refuge on Kaua‘i, where scientists and park rangers are doing all they can to help the endangered bird.

The threats to the koloa are by no means over. One of the most signiﬁcant today is the threat of genetic extinction through crossbreeding with mallards, a duck introduced to Hawai‘i in the 1800s. With crossbreeding, over time the koloa would gradually become koloa/mallard hybrids until no pure koloa remained. Such an extinction would be largely invisible because the koloa’s plumage looks mallard-like at different points in its life—so much so that even experts cannot always be 100 percent sure whether a duck is a hybrid or pure koloa. Another danger is avian botulism, a paralytic neurotoxin that infects maggots, which ducks are fond of eating; pond stagnation, as well as possible climate change-driven warming of pond waters, is creating conditions in which massive outbreaks of the fatal disease can occur. Other hurdles to the koloa’s survival include loss of wetland habitat; introduced predators like mongooses, cats and rats; and various invasive ﬁshes and weeds that destroy the bird’s food source.

Happily the koloa has a stronghold at the Hanalei National Wildlife Refuge on Kaua‘i, an island without an established mongoose population and with fewer introduced mallards, and it’s estimated that around half of the world’s koloa population calls the refuge home. “This is probably the most important site in the world for koloa,” says Uyehara, squinting at the mosaic of managed ponds glistening in the morning sun that she and the team work hard to maintain. The refuge is a pictur-esque expanse of 917 acres of green wetlands, taro ﬁelds, rivers and streams ﬂanked by the steep, jagged mountains that run inland from the one-lane bridge heading to Hanalei bay. The refuge beneﬁts more than just the koloa—several endan-gered birds thrive here. As koloa ﬂap fast and sleek overhead, ‘alae kea (Hawaiian coots) and ae‘o (Hawaiian black-necked stilts) splash about in the ponds, ‘alae ‘ula (Hawaiian common moorhens) call to each other from the low sedge, while on the road to the refuge’s ofﬁce, nēnē wander curiously alongside cars, examining tires and snifﬁng paintwork. Where else in the world can you see ﬁve endangered birds on one stretch of road?

Wetlands at the wildlife refuge.

The refuge has a tiny staff as well as two interns and a research assistant. The team lays and checks traps for predators, repairs fences, studies the birds and maintains the hundred acres of managed ponds, swamps, channels and openings that constitute the birds’ wetland homes. They also monitor avian botulism; refuge staff estimate they were losing one koloa every other day when the outbreaks were at their worst. They are working around the clock consulting soil specialists, ecologists and disease experts to discover what is triggering the outbreaks.

To keep the ponds as healthy as possible, the refuge employs an ingenious scheme of draining and reﬁlling them, adjusting the water level to suit the birds’ needs, encourage native plant growth and manage invasive weeds. After a year or two, once a pond is choked with California, paspalum and guinea grasses—aggressive weeds that grow even by moonlight—it is drained and the soil is reconditioned with heavy machinery.

The footsteps of Chad Smith, engineering equipment operator for the refuge, precede him as he crashes out of a stand of invasive grass that towers overhead. Smith, a man lauded for doing the work of four men, builds and takes care of all the refuge’s managed ponds and habitats as well as its ﬂeet of tractors and diggers. Once he has pushed back the invasives, the native plants quickly regenerate, providing food, nesting and cover. When the pond is reﬁlled with water, the koloa move in immediately. “We open up a new wetland, boom! They’re in there,” beams Uyehara. “They are like, ‘Thank you!’” Smith grins broadly and adds, “One of my greatest days was when we ﬁrst got one of these ponds. I was coming down the road, and I was actually frightened because there was this big black mass that came off the water. And it was just tons and tons of koloa; it was like three hundred koloa coming off the one pond.”

Christopher Malachowski in the refuge, preparing to band a koloa; he will also record the duck's measurements, age, gender and plumage traits.

Courtesy Sharon Donnelly

Chris Malachowski, the Oregon State student studying the koloa, has spent the last four years tracking the duck at the Hanalei Refuge, gathering more precise information about the bird’s habits and habitats than we’ve ever had before. He and his team banded a thousand koloa, attached radio transmitters to 115 birds and used satellite backpacks to monitor the movements of another eleven. Each day, research assistant Jillian Cosgrove drives around the refuge in a battered truck with a huge antenna mounted on top (built by Malachowski himself), stopping to tune in to the unique radio signal of each one of the ducks ﬁtted with transmitters. She spies koloa with a telescope, noting band numbers and locations; the birds wearing satellite packs can be tracked by computer from anywhere in the world. When he’s not out in the ﬁeld, Malachowski tracks them from his desk in Oregon. The data is still being sorted and analyzed, but it has already revealed an apparent dramatic gender skew in Hanalei koloa: The population is approximately 75 percent male, perhaps because the females are much more vulnerable to predation while they are nesting. It has also revealed that the number of koloa on the refuge increases dramatically at night.

A decade of exploration into the koloa’s genetics has also yielded results with profound implications for koloa conservation. “Understanding the genetics of this bird ended up being one of the most pivotal recovery actions,” explains Andy Engilis, curator of the Museum of Wildlife and Fish Biology at the University of California, Davis. Engilis collaborated with John Eadie at UC Davis as well as with cutting-edge genomic researchers at Wright State University in Ohio, the Smithsonian Institution and the US Fish and Wildlife Service. Their preliminary work is indicating that, in the absence of mallards, the genetic signature of koloa hybrids will drift back to almost pure koloa over time: For example, in the James Campbell National Wildlife Refuge on O‘ahu, an area where mallards have been successfully controlled, individual birds tested in the 1980s were found to be hybrids, whereas individual birds tested in 2005 showed a 95 percent assuredness of being genetically koloa. In other words: Remove the mallards, make sure that no more of them are introduced and the hybrids look likely to revert to their native state.

Malachowski prepares to release a koloa outfitted with a satellite transmitter, which will track the duck's movements for a year or more.

Courtesy Christopher Malachowski

Both the genetics work and Malachowski’s PhD are the result of broad collaborations between universities, specialists, agencies and individuals on the Mainland and here in the Islands, and have served to dramatically increase our knowledge about koloa. When Engilis began working with the duck in 2003, the main scientiﬁc study had been prepared by Gerald Swedberg in 1967, almost forty years earlier. This lack of information is not surprising given how difﬁcult the koloa is to study: You could camp out beside one of the refuge’s ponds for an hour and still be lucky to get a good glimpse of this wary bird. But the recent investments made to understand the duck’s history, ecology and genetics could ultimately end up saving it: The results of Malachowski’s and Engilis’ work will inform the creation of an action plan for recovery of the koloa.

And recovery looks possible. Many are conﬁdent that with the right support the koloa could get off the endangered species list and become a success story, a remark-able achievement in a time when many other endangered Hawaiian birds look likely to become extinct. “I think the Hawaiian duck is one species that, if it had the proper amount of federal and state resources, could be recovered,” states Engilis. “It should be a priority for us to recover something that is recoverable.”

Another upside is the koloa’s responsiveness. “I guess that’s why I really like working with ducks,” says Uyehara as she lowers the scope through which she’s been eyeballing a pair of koloa that are watching her from the opposite end of the pond. “You can see your efforts, and it’s very satisfying. Humans can make a difference. We cause their extinction, but we have the knowledge and the power to reverse it, too.” HH